#region Copyright & License

//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

using System;
using System.Text.RegularExpressions;
using log4net.Core;

namespace log4net.Filter {
  /// <summary>
  /// Simple filter to match a string in the rendered message
  /// </summary>
  /// <remarks>
  /// <para>
  /// Simple filter to match a string in the rendered message
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  public class StringMatchFilter : FilterSkeleton {
    #region Member Variables

    /// <summary>
    /// Flag to indicate the behavior when we have a match
    /// </summary>
    protected bool m_acceptOnMatch = true;

    /// <summary>
    /// A regex object to match (generated from m_stringRegexToMatch)
    /// </summary>
    protected Regex m_regexToMatch;

    /// <summary>
    /// A string regex to match
    /// </summary>
    protected string m_stringRegexToMatch;

    /// <summary>
    /// The string to substring match against the message
    /// </summary>
    protected string m_stringToMatch;

    #endregion

    #region Constructors

    #endregion

    #region Implementation of IOptionHandler

    /// <summary>
    /// Initialize and precompile the Regex if required
    /// </summary>
    /// <remarks>
    /// <para>
    /// This is part of the <see cref="IOptionHandler"/> delayed object
    /// activation scheme. The <see cref="ActivateOptions"/> method must 
    /// be called on this object after the configuration properties have
    /// been set. Until <see cref="ActivateOptions"/> is called this
    /// object is in an undefined state and must not be used. 
    /// </para>
    /// <para>
    /// If any of the configuration properties are modified then 
    /// <see cref="ActivateOptions"/> must be called again.
    /// </para>
    /// </remarks>
    public override void ActivateOptions() {
      if (m_stringRegexToMatch != null)
        m_regexToMatch = new Regex(m_stringRegexToMatch, RegexOptions.Compiled);
    }

    #endregion

    /// <summary>
    /// <see cref="FilterDecision.Accept"/> when matching <see cref="StringToMatch"/> or <see cref="RegexToMatch"/>
    /// </summary>
    /// <remarks>
    /// <para>
    /// The <see cref="AcceptOnMatch"/> property is a flag that determines
    /// the behavior when a matching <see cref="Level"/> is found. If the
    /// flag is set to true then the filter will <see cref="FilterDecision.Accept"/> the 
    /// logging event, otherwise it will <see cref="FilterDecision.Neutral"/> the event.
    /// </para>
    /// <para>
    /// The default is <c>true</c> i.e. to <see cref="FilterDecision.Accept"/> the event.
    /// </para>
    /// </remarks>
    public bool AcceptOnMatch {
      get { return m_acceptOnMatch; }
      set { m_acceptOnMatch = value; }
    }

    /// <summary>
    /// Sets the static string to match
    /// </summary>
    /// <remarks>
    /// <para>
    /// The string that will be substring matched against
    /// the rendered message. If the message contains this
    /// string then the filter will match. If a match is found then
    /// the result depends on the value of <see cref="AcceptOnMatch"/>.
    /// </para>
    /// <para>
    /// One of <see cref="StringToMatch"/> or <see cref="RegexToMatch"/>
    /// must be specified.
    /// </para>
    /// </remarks>
    public string StringToMatch {
      get { return m_stringToMatch; }
      set { m_stringToMatch = value; }
    }

    /// <summary>
    /// Sets the regular expression to match
    /// </summary>
    /// <remarks>
    /// <para>
    /// The regular expression pattern that will be matched against
    /// the rendered message. If the message matches this
    /// pattern then the filter will match. If a match is found then
    /// the result depends on the value of <see cref="AcceptOnMatch"/>.
    /// </para>
    /// <para>
    /// One of <see cref="StringToMatch"/> or <see cref="RegexToMatch"/>
    /// must be specified.
    /// </para>
    /// </remarks>
    public string RegexToMatch {
      get { return m_stringRegexToMatch; }
      set { m_stringRegexToMatch = value; }
    }

    #region Override implementation of FilterSkeleton

    /// <summary>
    /// Check if this filter should allow the event to be logged
    /// </summary>
    /// <param name="loggingEvent">the event being logged</param>
    /// <returns>see remarks</returns>
    /// <remarks>
    /// <para>
    /// The rendered message is matched against the <see cref="StringToMatch"/>.
    /// If the <see cref="StringToMatch"/> occurs as a substring within
    /// the message then a match will have occurred. If no match occurs
    /// this function will return <see cref="FilterDecision.Neutral"/>
    /// allowing other filters to check the event. If a match occurs then
    /// the value of <see cref="AcceptOnMatch"/> is checked. If it is
    /// true then <see cref="FilterDecision.Accept"/> is returned otherwise
    /// <see cref="FilterDecision.Deny"/> is returned.
    /// </para>
    /// </remarks>
    public override FilterDecision Decide(LoggingEvent loggingEvent) {
      if (loggingEvent == null)
        throw new ArgumentNullException("loggingEvent");

      string msg = loggingEvent.RenderedMessage;

      // Check if we have been setup to filter
      if (msg == null || (m_stringToMatch == null && m_regexToMatch == null))
        // We cannot filter so allow the filter chain
        // to continue processing
        return FilterDecision.Neutral;

      // Firstly check if we are matching using a regex
      if (m_regexToMatch != null) {
        // Check the regex
        if (m_regexToMatch.Match(msg).Success == false) // No match, continue processing
          return FilterDecision.Neutral;

        // we've got a match
        if (m_acceptOnMatch)
          return FilterDecision.Accept;
        return FilterDecision.Deny;
      } else if (m_stringToMatch != null) {
        // Check substring match
        if (msg.IndexOf(m_stringToMatch) == -1) // No match, continue processing
          return FilterDecision.Neutral;

        // we've got a match
        if (m_acceptOnMatch)
          return FilterDecision.Accept;
        return FilterDecision.Deny;
      }
      return FilterDecision.Neutral;
    }

    #endregion
  }
}